Hydrogen-Powered Vehicles: A Paradigm Shift in Sustainable Transportation

Abstract

The global shift towards sustainable energy solutions has prompted a reevaluation of traditional transportation methods. In this context, the replacement of electric cars with hydrogen-powered vehicles is emerging as a promising and transformative alternative. This publication explores the essence of this transition, highlighting the potential benefits and challenges associated with embracing hydrogen as a fuel source for automobiles. The purpose of this work is to provide a comprehensive comparison of electric vehicles (EVs) and hydrogen fuel cell vehicles (HFCVs), analyzing their respective advantages and disadvantages. Additionally, this work will outline the significant changes occurring within the automotive industry as it transitions towards sustainable mobility solutions.

1. Introduction

There has been considerable interest within the scientific community for several decades in the topic of hydrogen as an energy carrier. Due to the dwindling supplies of non-renewable energy sources such as natural gas and crude oil, coupled with a growing awareness of the impact of carbon dioxide released into the atmosphere on the condition of our planet, hydrogen is now considered a clean and efficient fuel. The desire for its widespread use brings with it many challenges—from production, through storage, to the efficient utilization of this gas in energy production processes. Hydrogen, a versatile and clean energy carrier, has diverse applications across various sectors. One of its primary uses is in fuel cells, where hydrogen reacts with oxygen to produce electricity, with water and heat as byproducts. This makes it an environmentally friendly alternative for powering electric vehicles, providing a longer range and quicker refueling compared to battery electric vehicles.

In the industrial sector, hydrogen is crucial for refining petroleum, producing ammonia for fertilizers, and manufacturing steel. It serves as a reducing agent, helping to convert raw materials into more usable forms while reducing carbon emissions.

Additionally, hydrogen is pivotal in energy storage. Surplus renewable energy can be used to produce hydrogen through electrolysis, which can later be converted back into electricity or used as a fuel, ensuring a stable energy supply even when renewable sources like wind and solar are not generating power (Figure 1).

The urgent need for sustainable energy solutions has catalyzed a profound reevaluation of traditional modes of transportation worldwide. As concerns about climate change, air pollution, and finite fossil fuel resources escalate, the imperative to transition to cleaner alternatives becomes increasingly apparent. In this transformative landscape, the potential replacement of electric cars with hydrogen-powered vehicles stands out as a promising and revolutionary alternative. This publication delves into the essence of this paradigm shift, examining the potential benefits and challenges that come with embracing hydrogen as a primary fuel source for automobiles [1].

However, despite its increasing popularity, potential shortages in essential battery components, such as lithium, nickel, and cobalt, may pose a threat to supplies. This raises the question of whether it is now opportune to shift focus towards hydrogen-based energy.

Developing hydrogen technologies is extremely important in environmental protection. Many studies prove that emissions from conventional vehicles pose a threat to the natural environment and pose a risk of degradation [2,3]. The most important are tests in real operating conditions for various groups of vehicles [4,5,6]. Although drive systems are constantly being developed, electric and hydrogen cars are the best prospects.

In contrast to Europe, where only a few hydrogen cars are available for purchase, accompanied by approximately 228 refueling stations, Asia is actively prioritizing hydrogen. The Japanese government, for instance, envisions having 800,000 hydrogen-powered vehicles on the roads by 2030, while China has set an ambitious target of 1 million by 2035 [7,8].

Japan’s commitment is expected to lead to cost reduction, increased production, and the establishment of a robust supply chain. However, the automotive industry remains divided, with few manufacturers investing in hydrogen, except for notable exceptions such as Toyota and Hyundai. Recently, BMW has rekindled its interest in hydrogen and foresees a complementary role for hydrogen-powered cars alongside battery electric vehicles.

The German automaker BMW plans to globally launch a small fleet of iX5 Hydrogen cars by the end of this year, primarily for testing purposes. “As a versatile energy source, hydrogen has a key role to play on the path to climate neutrality”, emphasized Oliver Zipse, Chairman of the Board of Management of BMW AG.

Similarly, the Stellantis Group has initiated limited production of commercial hydrogen delivery vehicles. However, not all major automakers share the same perspective; both Mercedes and Audi have shelved plans to introduce hydrogen fuel cell cars. The divergent strategies within the automotive industry reflect ongoing debates about the future of sustainable transportation and the role that hydrogen will play in achieving climate goals.

An electric vehicle relies on electricity stored in a battery, which is charged by connecting to the electric grid. In contrast, a hydrogen fuel cell electric vehicle generates its own electricity through a chemical reaction in the fuel cells. This electricity propels the wheel motors, and the sole byproduct is water vapor. Hydrogen fuel cell cars refuel at designated gas stations. The appeal of a hydrogen car lies in its ability to refuel in the same time frame as a petrol or diesel car and attain a comparable range, all while producing zero emissions [9,10].

2. Hydrogen: The Ultimate Energy Carrier

At the core of the periodic table lies hydrogen, the lightest element, existing as an odorless gas with a remarkably low boiling point of 20.28 K [11,12]. The combustion of a kilogram of hydrogen releases a staggering 142 MJ of energy, dwarfing the heat generated by hydrocarbons, typically ranging from 40 to 60 MJ/kg [13]. Moreover, unlike fossil fuels, the combustion of hydrogen yields no pollutants such as CO₂, NO_x, or SO_x, only water. These attributes position hydrogen as a pivotal player in the transition towards clean and efficient energy sourced from renewables.

The journey of hydrogen as an energy carrier traces back to 1807 when François Isaac de Rivaz engineered the first vehicle powered by a spark-ignition engine running on a blend of hydrogen and oxygen. Initially modest—a small transport cart—this invention evolved over subsequent decades, notably enhanced by Jean Lenoir, leading to the production of vehicles on a commercial scale [11,12]. Subsequently, hydrogen technology underwent significant transformations, notably finding its propulsion role in the realm of space exploration since the 1970s, serving as rocket fuel. During the launch of a space shuttle, nearly 3 million liters of liquid hydrogen are consumed—an irreplaceable resource. Considering not only energy efficiency but also factors like fuel weight and emissions during combustion, an alternative to hydrogen remains inconceivable.

The second, significantly more promising avenue for utilizing hydrogen as an energy carrier with regard to energy conversion efficiency is through fuel cells, particularly hydrogen–oxygen cells (see Figure 2). Among these, the most commonly discussed are proton exchange membrane fuel cells (PEMFCs), also known as polymer electrolyte membrane fuel cells, available in both low- and high-temperature variants [14]. Their notable advantage lies in the presence of a solid-phase electrolyte—typically a polymer, often perfluorinated—which enhances system safety and efficiency [15]. Additionally, they boast high power density, rapid startup times, and a theoretical efficiency of up to 83% at room temperature [16].

Operational requirements entail the supply of two gases—oxygen to the cathode and hydrogen to the anode. Electrodes are segregated by a semi-permeable membrane, facilitating the flow of H⁺ protons generated through hydrogen oxidation at the anode. Upon reaching the cathode, these protons combine with O²⁻ anions produced therein (Figure 2). Simultaneously, electrons yielded during the hydrogen oxidation process power the electric motor. Analogous to hydrogen combustion, the sole byproducts of the redox process are pure water and heat. While the practical efficiency of PEMFCs stands at 65%, substantial enhancements in efficiency are conceivable through the utilization of released heat in cogeneration systems [17,18,19]

It is crucial to bear in mind that hydrogen is not an energy source in itself; rather, it functions solely as an energy carrier, facilitating its storage and transport in a readily usable form. Consequently, pivotal aspects in the advancement of hydrogen technology revolve around its production and storage methods.

3. Fuel Cells: Technological Challenges

3.1. General Comments

Hydrogen-powered vehicles (HPVs) are increasingly seen as a viable alternative to traditional internal combustion engine vehicles and battery electric vehicles (BEVs). This part explores the potential for cost competitiveness in HPVs, current research efforts addressing existing challenges, and an overview of key startups and patents in the hydrogen technology space.

Fuel cell costs: fuel cell technology is expensive due to the use of rare and expensive materials like platinum. Fuel cell technology, particularly proton exchange membrane (PEM) fuel cells, relies heavily on the use of platinum as a catalyst. Platinum’s unique properties make it highly effective in facilitating the chemical reactions necessary for generating electricity from hydrogen and oxygen.

However, the reliance on platinum presents several challenges: platinum is one of the most expensive metals, with prices fluctuating based on market demand and supply constraints. As of mid-2024, the price of platinum is around USD 1000 per ounce. This high cost significantly impacts the overall cost of fuel cells, making them less competitive compared to traditional internal combustion engines and even some battery technologies. Geopolitical issues: the supply of platinum is concentrated in a few countries, notably South Africa and Russia. This concentration poses risks related to geopolitical stability and trade restrictions. Mining challenges: platinum mining is energy-intensive and environmentally damaging, which further complicates its use in green technologies.

Platinum is an expensive and valuable metal that is widely used in the production of catalysts, electronic devices, aerospace materials, biomedical instruments, and jewelry, amid other uses, due to its chemical resistance, high-temperature stability, and reliable electrical properties. Natural reserves of platinum and platinum group metals (PGMs; including platinum, palladium, rhodium, ruthenium, iridium, and osmium) are finite, primarily found in Russia, North America, Canada, and South Africa. The concentration of PGMs in ores is low, typically 2–10 ppm (g/t), and they are commonly associated with base-metal sulfides. PGMs are extracted as by products or coproducts according to their ore concentration. Global demand for platinum is rising due to its broad applications across diverse industries.

Platinum is used in PEM fuel cells because of its excellent catalytic properties, which enhance the performance of the fuel cell. Researchers are working to reduce the amount of platinum required without compromising performance. However, even small reductions in platinum loading can lead to significant cost savings. Platinum catalysts can degrade over time, reducing the lifespan of the fuel cell. This degradation is a major focus of current research, as improving durability can reduce long-term costs. Fuel cells operate under harsh conditions, including high temperatures and acidic environments, which accelerate the degradation of platinum.

Non-platinum catalysts: researchers are exploring alternative materials such as palladium, cobalt, nickel, and iron-based catalysts. These materials are less expensive and more abundant than platinum but currently lack the same efficiency and durability.

Nanostructured catalysts: advances in nanotechnology are leading to the development of nanostructured catalysts that use platinum more efficiently or replace it altogether. These catalysts can provide a larger surface area for reactions, potentially reducing the amount of platinum needed. Developing ultra-thin platinum films can reduce the amount of platinum used while maintaining catalytic efficiency.

Creating platinum alloys with other metals can improve performance and reduce costs. For example, platinum–nickel and platinum–cobalt alloys have shown promise in enhancing catalytic activity and durability. Innovations in catalyst design, such as core–shell nanoparticles, where a non-precious metal core is coated with a thin platinum shell, are being explored to maximize the efficiency of platinum usage. Transitions metals, often combined with nitrogen-doped carbon supports, show promise but require further development to match the performance of platinum.

Novel materials: carbon-based materials, including graphene and carbon nanotubes, are being investigated for their potential catalytic properties and cost-effectiveness. Single-atom catalysts (SACs), where individual platinum atoms are dispersed on a support material, offer the potential for maximum catalytic efficiency with minimal platinum use. Biomimetic catalysts: inspired by natural enzymes, biomimetic catalysts aim to replicate the efficiency of biological processes in hydrogen oxidation and oxygen reduction reactions.

Improved methods for recycling platinum from spent fuel cells and catalytic converters can help mitigate supply issues and reduce costs. Enhancing the efficiency of platinum recovery processes is crucial for making fuel cells more sustainable and economically viable.

The rate at which high-grade PGM resources are being depleted has been speeding up due to growing demand, while production costs have been increasing as the concentration of PGMs in the surviving natural ores diminishes. Consequently, it is essential to process secondary materials like spent catalysts, electronic waste, used equipment, manufactured goods, and membrane electrode assemblies to recover and recycle platinum. This approach will help preserve resources to meet future demands for platinum and other PGMs while also reducing environmental pollution. Platinum is widely used as a catalyst in numerous chemical reactions, making spent catalysts a significant secondary source for recovering platinum and other related metals.

3.2. Alternative Catalysts for Hydrogen Production

3.2.1. Transition Metal Catalysts

Transition metals such as iron, nickel, and cobalt are being investigated as low-cost alternatives to noble metal catalysts such as platinum in hydrogen production processes. These metals can be combined with other elements (such as nitrogen or phosphorus) to create alloys or compounds that exhibit good catalytic properties for the hydrogen evolution reaction (HER) or oxygen evolution reaction (OER) [20,21].

Nickel-iron alloys (NiFe): these have been shown to exhibit good catalytic activity for the OER under alkaline conditions, reducing the dependence on noble metals. Molybdenum-based catalysts: molybdenum disulfide (MoS₂) has been widely studied as a highly active, low-cost catalyst for the HER. When combined with other materials or in nanostructured form, MoS₂ can exhibit enhanced performance similar to platinum [22,23].

3.2.2. Metal–Organic Frameworks (MOFs)

Metal–organic frameworks (MOFs) are crystalline materials consisting of metal ions coordinated with organic ligands to form porous structures. They offer a large surface area and tunable pore sizes, making them attractive for catalysis. MOFs can incorporate transition metals such as cobalt or nickel, enhancing their catalytic properties for hydrogen evolution and oxidation reactions. The porous nature of MOFs enables efficient hydrogen capture and release, making them potential dual-purpose materials for both catalysis and storage [24,25,26].

3.2.3. Single-Atom Catalysts (SACs)

Single-atom catalysts consist of isolated metal atoms dispersed on a support material (such as graphene or carbon nitride). SACs maximize catalytic efficiency by ensuring that all metal atoms are exposed and active. SACs have shown exceptional performance in the HER and OER due to their unique electronic properties and high surface activity. For example, single-atom cobalt or nickel catalysts have shown promising results in reducing overpotentials in water splitting. They are also more cost-effective compared to traditional catalysts because they require minimal amounts of metal [27,28].

3.2.4. Enzyme Mimetic Catalysts

These are synthetic materials designed to mimic the active sites of natural enzymes (such as hydrogenases) that catalyze hydrogen production in biological systems. Bio-inspired catalysts are typically composed of materials abundant on Earth, such as iron, nickel, or cobalt, and are designed to replicate natural enzymatic processes for hydrogen production. Such catalysts have the potential to operate under mild conditions, increasing their efficiency and sustainability [29].

3.2.5. Photocatalysts for Solar-Powered Hydrogen Production

Photocatalysts are materials that can absorb sunlight and use this energy to drive chemical reactions, such as splitting water into hydrogen and oxygen. Titanium dioxide (TiO₂), doped with other elements or combined with materials such as graphene, has shown potential for photocatalytic hydrogen production. Perovskite-based materials are also being studied for their ability to absorb a wide range of wavelengths of light, making them efficient photocatalysts for solar-powered hydrogen production [30,31,32].

3.3. Hydrogen Storage Solutions

3.3.1. Compressed Gas Storage

Compressed hydrogen storage involves storing hydrogen at high pressure (typically 350–700 bar) in specially designed tanks. Carbon-fiber-reinforced tanks are lightweight and strong solutions that can withstand high pressures. Advances in materials science are aimed at reducing the weight and cost of these tanks while increasing their storage capacity. Compressed storage is currently one of the most mature and commercially available technologies, used in fuel cell vehicles and stationary storage [33].

3.3.2. Liquid Hydrogen Storage

Hydrogen can be stored as a cryogenic liquid at temperatures below −253 °C. Cryogenic tanks are double-walled, vacuum-insulated tanks used to store liquid hydrogen, minimizing heat transfer and hydrogen evaporation. This method provides higher energy density compared to compressed gas. Liquid hydrogen storage is often used in applications where high-density energy storage is critical, such as space exploration [33].

3.3.3. Metal Hydrides

Metal hydrides are materials that absorb hydrogen gas and store it in solid form by forming metal–hydrogen bonds. Magnesium hydride (MgH₂) is a lightweight and relatively common material with good hydrogen storage capacity. Research is focused on improving its absorption and desorption rates, which are currently low at moderate temperatures. Complex hydrides (such as sodium alanate) can release hydrogen at lower temperatures and have been studied for applications where reversible hydrogen storage is required [34].

3.3.4. Chemical Hydrogen Storage

Chemical hydrogen storage involves the use of materials that can release hydrogen through chemical reactions. Ammonia (NH₃) is a traction hydrogen carrier because it has a high hydrogen content (17.6% by weight) and is easier to store and transport than pure hydrogen. Ammonia can be decomposed to release hydrogen using catalysts, but developing efficient catalysts for this process remains a challenge. Liquid organic hydrogen carriers (LOHCs) are organic compounds, such as methylcyclohexane, that can absorb and release hydrogen through reversible chemical reactions. LOHCs offer a liquid-phase storage solution that can be integrated into existing fuel infrastructure [35].

3.3.5. Adsorption-Based Storage

Adsorption-based storage involves storing hydrogen in porous materials at relatively low pressures. Activated carbon and MOFs are large-surface-area materials that can adsorb significant amounts of hydrogen. Research is focused on increasing the adsorption capacity and stability of these materials. Among the nanostructured materials, carbon nanotubes and graphene are being studied for their unique properties that enable hydrogen adsorption at the molecular level, potentially offering a compact and efficient storage solution [36,37].

3.3.6. Solid-State Hydrogen Storage

In solid-state storage, hydrogen is stored in a solid material such as hydrides or some chemical compounds. Borohydrides and ammonia borate are materials that have high hydrogen density and can release hydrogen upon heating. However, they require careful handling and optimization to improve the kinetics and reversibility of hydrogen release. Graphene-based materials, on the other hand, are advanced materials such as graphene, which can also be designed to store hydrogen by binding it to surfaces or within structures [38].

Hydrogen storage and production using alternative catalysts are key to the development of the hydrogen economy. Advanced catalysts such as transition metals, MOFs, and single-atom catalysts promise lower costs and improved hydrogen production efficiency. On the other hand, new hydrogen storage solutions, from metal hydroxides to LOHCs, offer a variety of paths to safe, efficient, and cost-effective hydrogen storage. Continued innovation in these areas is essential for the widespread adoption of hydrogen as a clean energy carrier [39].

4. Preferred Criteria for Hydrogen Storage in Automotives and the Possibility of Using It in Microgrids

Road transportation stands as a prominent intended application for hydrogen fuel cells, offering a promising avenue for mitigating pollution typically associated with combustion engines, as the sole byproduct of the chemical reactions within fuel cells is water. Nevertheless, engineers and scientists are confronted with the challenge of devising suitable tanks to facilitate the supply of hydrogen to these cells. The list of these technical parameters includes not only such basic features of fuel tanks as charging time, efficiency, or cost but also much more importantly, from the electrochemical point of view, capacity issues (

Table 1. Selected requirements for hydrogen storage for use in light vehicles.

	2020	2025	Target
Gravimetric capacity [g/kg]	45	55	65
Volumetric capacity [g/dm3]	30	40	50
Storage cost [$/kg]	333	300	266
Ambient temperature [°C]	−40 to +60	−40 to +60	−40 to +60
Delivered hydrogen temperature [°C]	−40 to +85	−40 to +85	−40 to +85
Released hydrogen pressure [bar]	5 to 12	5 to 12	5 to 12
Charging time [min]	3 to 5	3 to 5	3 to 5
Capability [%]	90	90	90

).

Crucial parameters in chemical hydrogen storage encompass hydrogen mass capacity, release temperature, process reversibility, and gas purity [40,41,42,43]. These four physicochemical attributes serve as pivotal indicators to assess the potential success of a given material in subsequent implementation studies. Given the inherently low density of hydrogen gas (0.0838 g/dm³ at 20 °C) [44], necessitating prohibitively large tanks for satisfactory use in automotive applications, the Department of Energy (DOE) has established a target hydrogen volume capacity of 30–50 g/dm³, roughly 500 times denser. Overcoming this challenge mandates exploration of alternative hydrogen storage methods beyond its gaseous state. Moreover, the DOE’s current hydrogen mass capacity target stands at 6.5%, a seemingly modest figure yet a formidable benchmark to achieve.

It is important to note that the mass capacity of hydrogen is determined by the ratio of the mass of stored hydrogen to the total mass of the system, including the fuel, tank, and components required for gas regulation, such as cables. Consequently, both the tank material and its contents are critical factors.

Another significant parameter is the purity of hydrogen. Given the aim of replacing traditional fuels with hydrogen to reduce air pollution, the by products of hydrogen release from the tank must not comprise other gases, particularly toxic ones. Additional gases could contaminate electrodes, alter the electrolyte’s pH, or harm membranes utilized in fuel cells, leading to a considerable decrease in efficiency [45,46,47]. Moreover, in chemical storage facilities, such contamination could pose issues with process reversibility, requiring the introduction of other substances besides hydrogen to restore the pre-discharge state of the tank.

The DOE requirements regarding hydrogen release temperature lack clarity. On one hand, the tank must not release gas inadvertently, such as when the vehicle is parked in a sunny location, considering ambient temperatures ranging from −40 °C to 60 °C. On the other hand, the hydrogen supplied to the fuel cell should not exceed 85 °C (assuming the use of low-temperature cells). This can be achieved either by releasing the gas at a temperature below 85 °C or by cooling it between the tank and the cell. Consequently, the optimal hydrogen release temperature falls within the range of 60–85 °C, with slightly higher values deemed acceptable.

Many individuals believe that potential violent reactions between hydrogen and oxygen could result in more severe consequences from damage to a car’s tank compared to a leak of conventional gasoline. However, research commissioned by the DOE has demonstrated that a hydrogen tank leak is considerably less hazardous than one involving gasoline. This discrepancy in risk stems largely from the difference in fuel densities—hydrogen, being a light gas, rapidly disperses, creating a flame column, whereas gasoline, a viscous liquid, spreads beneath the vehicle, with its flammable vapors dispersing and potentially leading to the vehicle’s total destruction. Nonetheless, such considerations must be thoroughly addressed when designing hydrogen storage facilities for mobile applications [48,49,50].

Hydrogen’s superior energy storage and density characteristics (Figure 3) offer a distinct advantage over traditional battery-based electric vehicles. The energy density of hydrogen allows for longer ranges without compromising vehicle weight or performance. This key attribute addresses some of the limitations associated with battery technologies, providing a compelling case for hydrogen as a viable alternative.

While the potential benefits of hydrogen-powered vehicles are compelling, challenges remain. Infrastructure development, including the establishment of a robust network of hydrogen refueling stations, is a critical hurdle that requires strategic planning and investment. Additionally, the energy-intensive process of hydrogen production needs to evolve towards greener methods to ensure the overall environmental sustainability of the hydrogen fuel cycle.

As the world undergoes a transformative shift towards sustainability, the prospect of replacing electric cars with hydrogen-powered vehicles emerges as a promising and dynamic alternative. From addressing environmental imperatives to offering versatile applications and reducing dependencies on rare resources, hydrogen’s potential benefits are substantial. Nevertheless, recognizing and overcoming challenges, particularly in infrastructure and production methods, is crucial for realizing the full potential of hydrogen as a clean and efficient fuel source. This publication encourages a nuanced exploration of the opportunities and obstacles in the journey towards a future where hydrogen-powered vehicles play a pivotal role in reshaping the landscape of sustainable transportation (Figure 4).

Hydrogen-powered vehicles offer a compelling advantage in terms of efficiency and range. Unlike electric vehicles that depend on batteries, hydrogen cars generate electricity through fuel cells, enabling longer driving ranges without the need for frequent recharging [51,52]. This characteristic addresses the common concern of “range anxiety” associated with electric vehicles, making hydrogen cars a viable option for a wider range of consumers [53]. The efficiency and extended driving range of hydrogen-powered vehicles mark a significant leap forward in automotive technology. Unlike electric vehicles that rely on battery storage, hydrogen cars utilize fuel cells to generate electricity through a process known as electrochemical conversion. This not only enhances overall efficiency but also allows for prolonged driving ranges without the necessity for frequent recharging [54].

Fuel cells facilitate a continuous and direct conversion of hydrogen into electricity, providing a more efficient power delivery system compared to the energy losses incurred during charging and discharging cycles in batteries. This inherent efficiency contributes to optimized energy utilization and, consequently, a longer driving range on a single fill of hydrogen.

The extended range is not only advantageous for personal transportation but also holds great potential for commercial and industrial applications, such as delivery fleets, where continuous and extended operation is critical [55]. Hydrogen-powered commercial vehicles can address the logistical challenges associated with electric counterparts, making them a versatile and efficient choice for various sectors [56].

The increased driving range of hydrogen-powered vehicles aligns well with existing infrastructure and driving habits, as refueling with hydrogen is a quick and straightforward process. This compatibility with current practices enhances the overall appeal of hydrogen vehicles and contributes to a smoother transition for consumers accustomed to traditional refueling methods [57,58]. As technological advancements continue to refine fuel cell technology, the efficiency and range of hydrogen vehicles are likely to further enhance, solidifying their role as a key player in the future of sustainable mobility.

One of the drawbacks of electric vehicles is the time required for recharging. Hydrogen vehicles can refuel quickly, similar to traditional gasoline-powered cars, making them more convenient for individuals with busy schedules. The ability to refuel rapidly contributes to the widespread acceptance of hydrogen-powered vehicles as a practical and efficient mode of transportation.

The reduced charging time of hydrogen vehicles brings about a paradigm shift in the user experience. Unlike the hours required for electric vehicles to achieve a full charge, hydrogen cars can refuel in a matter of minutes, closely mirroring the familiar and efficient process associated with traditional internal combustion engines. This notable advantage fosters a seamless transition for consumers, eliminating the need for significant alterations in their daily routines.

The quick refueling time of hydrogen-powered vehicles enhances their practicality for long-distance travel, road trips, and other scenarios where the urgency to resume travel is paramount. This attribute expands the range of use cases for hydrogen cars, making them a versatile choice for drivers who prioritize both sustainability and practicality in their daily lives.

The rapid refueling feature of hydrogen vehicles dovetails well with existing fueling infrastructure. As hydrogen refueling stations continue to expand, the compatibility with conventional refueling methods adds an extra layer of convenience for consumers. This ensures that the transition to hydrogen-powered vehicles is not only efficient but also seamlessly integrated into existing transportation ecosystems. The ability to refuel quickly contributes significantly to the overall acceptance of hydrogen-powered vehicles.

Microgrids, or localized energy systems capable of operating independently or connected to the main grid, are increasingly integrating renewable energy sources such as solar and wind. However, these renewable energy sources are intermittent and require reliable energy storage solutions to ensure a steady supply. The multi-faceted development of micronetworks is essential for creating innovations in the field of energy management. Studies [59,60,61] provide valuable perspectives on various aspects of multi-energy systems and hydrogen integration, and they provide significant context for understanding the broader landscape of energy management strategies.

Hydrogen offers an attractive solution, serving as both a clean energy carrier and a versatile storage medium. Integrating hydrogen into microgrids can increase their flexibility, reliability, and sustainability. Hydrogen provides a robust energy storage solution by converting excess renewable energy into hydrogen via electrolysis. This stored hydrogen can then be converted back into electricity using fuel cells when needed. Unlike batteries, which have a limited storage life and degrade over time, hydrogen storage can be more easily scaled to meet long-term energy needs [62,63].

In a simulated microgrid environment, hydrogen storage systems demonstrated a 30% increase in storage capacity compared to lithium-ion batteries for long-term storage, especially during periods of low renewable generation [64,65]. This resulted in a 20% reduction in energy curtailment, demonstrating improved flexibility and utilization of renewable energy.

By incorporating hydrogen into microgrids, communities can increase their resilience to power outages and grid failures. Hydrogen fuel cells can provide continuous and reliable power, making microgrids less dependent on the central grid. This is particularly beneficial for remote or disaster-prone areas. A study comparing a hydrogen-integrated microgrid and a traditional battery-based microgrid in a coastal region prone to hurricanes showed that the hydrogen-based system maintained power for 48 h longer during a simulated power outage, providing a critical advantage in terms of resilience and reliability [64].

Hydrogen, especially when produced using renewable energy (green hydrogen), is a zero-emission fuel that supports microgrid decarbonization. It helps reduce dependence on fossil fuels and contributes to meeting stringent environmental regulations and sustainable development goals. A life-cycle assessment comparing a hydrogen-powered microgrid with a diesel-generator-based microgrid showed that the hydrogen system reduced CO2 emissions by 90%, as well as other pollutants such as NO_x and particulate matter by more than 80% [63,66].

Hydrogen can be used not only for electricity generation but also for heating, transportation, and industrial processes, providing multiple value streams to microgrids. This versatility makes hydrogen a scalable solution that can adapt to a variety of energy needs and microgrid applications. In the comparative analysis, a microgrid using hydrogen for both power and heating demonstrated a 25% reduction in total energy costs compared to a microgrid relying solely on electricity storage [62,64]. The study found that hydrogen’s ability to perform multiple functions contributed to lower operating costs and greater scalability.

Integrating hydrogen into microgrids can spur local economic growth and job creation in sectors such as hydrogen production, fuel cell manufacturing, and infrastructure development. This economic benefit is particularly significant in regions investing in clean energy technologies. A study of the economic impact of two communities—one with a hydrogen-based microgrid and the other with a conventional energy system—found that the hydrogen-using community saw a 15 percent increase in local clean energy employment over three years, compared with little change in the control community [64].

5. The Operational Sequence of HFCVs

Hydrogen fuel cell vehicles (HFCVs) operate on the principle of harnessing the electrochemical reaction involving hydrogen and oxygen that generates electricity, which in turn powers an electric motor to propel the vehicle [67]. The working principle of HFCVs involves several key steps (Figure 5) [68,69].

• Hydrogen fuel storage: HFCVs store hydrogen gas in high-pressure tanks. The hydrogen can be produced through various methods, such as electrolysis or reforming of natural gas.
• Electrochemical reaction in fuel cells: the core component of a hydrogen fuel cell vehicle (HFCV) is the fuel cell stack, made up of numerous individual fuel cells. Each fuel cell comprises an anode and a cathode separated by an electrolyte membrane, often made of proton exchange membrane (PEM) or alkaline materials. Hydrogen gas is fed to the anode, where it undergoes a chemical reaction known as electrolysis. During this reaction, hydrogen molecules are divided into protons (H⁺) and electrons (e⁻).
• Electron flow and electrical current: the electrons produced in the anode side cannot traverse the electrolyte membrane, so they are forced to travel through an external circuit, generating an electric current that can be harnessed for electrical power.
• Proton migration through electrolyte: simultaneously, protons migrate through the electrolyte membrane to the cathode side.
• Oxygen reaction at the cathode: on the cathode side, oxygen from the air is introduced, and it reacts with electrons and protons that have traveled through the external circuit. This process produces water (H₂O) as a waste product.
• Generation of electricity: the combination of electrons flowing through the external circuit and protons migrating through the electrolyte creates an electric current. This electrical energy can be utilized to power the electric motor of the vehicle, providing the necessary propulsion.
• Emission of water vapor: the only direct emission from the hydrogen fuel cell vehicle is water vapor, making HFCVs environmentally friendly. The overall reaction in the fuel cell can be represented as: 2H₂ + O₂ → 2H₂O.
• Efficiency and energy conversion: hydrogen fuel cells are known for their high efficiency in converting chemical energy into electricity. The energy efficiency of HFCVs is generally higher compared to internal combustion engine vehicles, and they offer the advantage of zero tailpipe emissions.

Hydrogen ionization begins at the anode, where a catalyst, typically composed of platinum, facilitates the ionization of hydrogen. Each hydrogen molecule (H₂) undergoes a split, producing two hydrogen ions (protons) and two electrons [70]:

H₂→2H⁺ + 2e⁻,

(1)

Within the proton exchange membrane (PEM) located in the fuel cell, only protons are allowed to pass through, while electrons are compelled to travel through an external circuit to reach the cathode. This electron movement generates an electric current.

Moreover, within the vehicle, hydrogen gas, stored in a high-pressure tank, is delivered to the anode side of the fuel cell.

On the cathode side, oxygen from the air is reduced and combines with incoming protons and electrons from the external circuit. This results in the formation of water as the sole byproduct [71]:

O₂ + 4H⁺ + 4e⁻ →2H₂O ΔH = −571.6 kJ/mol

(2)

This indicates that the reaction is highly exothermic. In a fuel cell, this enthalpy change is partly converted into electrical energy. The negative value represents the total energy released when hydrogen and oxygen combine to form water, with part of this energy manifesting as electrical energy and part as heat.

The electricity generated, represented by the flow of electrons, is utilized to power the vehicle’s electric motor and other electrical systems [72]. The flow of electrons through the external circuit represents the electrical current. This generated electricity is harnessed to power the vehicle’s electric motor and additional electrical components. The overall chemical reaction occurring in the fuel cell can be described as:

2H₂ + O₂ →2H₂O + ELECTRICAL ENERGY ΔH = −571.6 kJ/mol

(3)

The kinetics and thermodynamics governing the processes occurring in a hydrogen fuel cell, crucial for the operation of hydrogen fuel cell vehicles (HFCVs), revolve around two fundamental processes. Firstly, there is the breaking of the H–H bond in hydrogen molecules, a process occurring at the anode. Simultaneously, there is the second process involving the formation of the O–H bond in water molecules, unfolding at the cathode.

In the anode, where hydrogen gas is supplied, the fuel cell initiates the dissociation of hydrogen molecules, separating them into protons and electrons. This breaking of the H–H bond is a pivotal step that releases electrons, which then contribute to the electric current in the external circuit [73].

The spontaneity of these reactions depends on the Gibbs free energy change (ΔG), determined using the following equation:

ΔG = ΔH − TΔS

(4)

where:

• ΔH—the enthalpy change,
• T—the absolute temperature,
• ΔS—the entropy change.

In a hydrogen fuel cell, ΔH primarily results from the energy difference between breaking H–H bonds and forming O–H bonds, and ΔS is typically negative due to a reduction in the number of gas molecules.

The Gibbs free energy change is also connected to the electrochemical potential (E) of the fuel cell by:

ΔG = −nFE

(5)

where:

• n—the number of electrons transferred per molecule of hydrogen (in this case, n = 2),
• F—the Faraday constant,
• E—the cell potential.

The cell potential is crucial for driving the electric current in the external circuit.

In essence, the power generation in HFCVs involves the orchestrated electrochemical reactions in the fuel cell, from hydrogen ionization to oxygen reduction, culminating in the production of electrical energy that powers the vehicle’s propulsion and electrical components.

The favorable thermodynamics (negative ΔG) and fast reaction rates (enhanced by catalysts) of the hydrogen oxidation and oxygen reduction reactions make hydrogen fuel cell vehicles (HFCVs) a promising technology for sustainable transportation, although the specific values of ΔG, ΔH, and ΔS depend on the fuel cell’s design and operating conditions [74].

6. Distinguishing Electric and Hydrogen Cars

6.1. Energy Storage

The way energy is stored differs between battery electric cars and hydrogen vehicles. In traditional electric vehicles, energy is drawn from a battery [75]. In contrast, hydrogen-powered vehicles are equipped with tanks holding compressed hydrogen. This hydrogen is fed into fuel cells, where it reacts with oxygen to generate electricity. For some, the technology used in hydrogen cars presents a promising alternative to the batteries found in electric vehicles. The disadvantages of batteries often include the fact that, despite the efforts of manufacturers, they still weigh too much, are large, and charging them can take a very long time—especially if we replenish energy at home [76].

• Electric cars: rely on batteries to store electrical energy,
• Hydrogen cars: utilize fuel cells to convert hydrogen into electrical energy.

6.2. Dexterity

The issue of efficiency is, for now, the key drawback of hydrogen cars. Even at the hydrogen production stage via electrolysis, up to 45% of the initial energy is lost (Figure 6). However, the losses do not end there. The subsequent stages of the process include compression, liquefaction, transport, filling, and generating energy in the fuel cell. When a vehicle converts hydrogen into electricity, just over half of the remaining energy is lost [77]. This means that the final efficiency of a hydrogen car may be only about 25–35%. Energy losses are much lower in electric cars equipped with a battery. Transporting electricity to the battery consumes only 8% of energy. In turn, when converting electricity into energy that sets the vehicle in motion, losses are estimated at approximately 18%. Ultimately, an efficiency of 70–80% can be expected. It is worth noting, however, that the efficiency of cars may be lower or higher depending on the specific model.

• Electric cars: efficient in converting stored energy into motion,
• Hydrogen cars: exhibit high efficiency, particularly in long-range applications.

6.3. Reception

In terms of range, hydrogen vehicles typically surpass conventional electric cars. The extended range of hydrogen cars makes them well suited for longer journeys, while electric cars are generally more appropriate for shorter trips, such as those within a city. However, this can vary depending on the specific model; some hydrogen-powered vehicles offer ranges comparable to those of battery electric cars [78].

• Electric cars: widely adopted globally, with increasing popularity,
• Hydrogen cars: still in the early stages of adoption, with limited availability.

6.4. Price and Operating Costs

In terms of costs, buying an electric car is generally more economical than purchasing a hydrogen vehicle. Many experts emphasize that they are a very economical solution [79]. Let us start with the fact that hydrogen cars cost more than battery electric cars. However, in the case of hydrogen-powered cars, one will pay more not only for the vehicle itself—the costs of operating the vehicle, including refueling, are also higher [80]. Hydrogen and other e-fuels (synthetic fuels) are more expensive due to the higher energy requirements for their production. Electric cars with batteries not only benefit from lower charging costs but also have a significantly better energy efficiency compared to hydrogen vehicles.

• Electric cars: generally more affordable, with lower operating costs,
• Hydrogen cars: tend to have higher upfront costs, but operating costs may vary based on factors like fuel prices.

6.5. Refueling

The speed of car charging is an issue in which hydrogen cars excel. In their case, refueling takes only a few minutes [81]. For this reason, they can be a very good alternative for longer routes to classic electric cars. In the case of cars with batteries, the energy replenishment time depends primarily on the electric car charger and the charger built into the vehicle. Charging an electric car can take up to 20 h if charged at home from a traditional socket. However, acquiring a faster charger or a wallbox tailored for a specific model can reduce this time to just a few hours.

• Electric cars: recharged through power outlets or charging stations,
• Hydrogen cars: refueled at specialized hydrogen refueling stations.

The issue of access to charging infrastructure certainly favors classic electric cars. This type of vehicle is much more popular than hydrogen cars, which is also reflected in the number of charging points for public use. Let us emphasize, however, that in Poland the infrastructure for charging electric cars is still being developed [82]. The number of available stations is not impressive, but it is still growing. Therefore, even when going on a longer route, one should not have too much trouble replenishing energy during the trip. In turn, access to hydrogen car charging infrastructure is very limited. One of the biggest obstacles currently standing in the way of the development of this technology are the huge costs associated with the need to build new stations and create appropriate distribution networks. Let us add that, taking into account the relatively low efficiency and price compared to the fuel used in cars with engine drive, such a huge investment does not seem profitable—at least when it comes to the passenger car segment [83].

• Electric cars: benefit from a more established charging infrastructure, with widespread availability of charging stations,
• Hydrogen cars: face challenges in terms of the limited availability of hydrogen refueling stations.

By examining these facets, consumers can make informed decisions based on their preferences, needs, and the existing infrastructure in their region. Both electric and hydrogen cars contribute to sustainable transportation, each with its unique advantages and considerations [84]. Hydrogen cars are expected to play an important role in the automotive market. According to specialists, such vehicles may prove useful in rail, sea, and aviation transport in the future [85,86]. This solution is also likely to be well accepted in vehicles intended for very long routes, e.g., in truck transport [87].

7. Cars with Alternative Propulsion—Fuel Cells

Addressing the challenge of reducing CO₂ emissions, set forth by new standards from the European Union, stands as one of the primary hurdles for contemporary car manufacturers. Beyond adhering to lower carbon dioxide emissions, top brands are confronted with the expectations of drivers who seek vehicles that are not only environmentally friendly but also economical. Striking a balance without compromising on performance, safety, or operating costs is paramount [88,89,90].

In response, manufacturers are introducing electric cars with batteries or hydrogen-powered cars as alternatives to traditional combustion vehicles. It is crucial to note that electricity, when sourced from the environment in an entirely ecological and sustainable manner, can contribute significantly to CO₂ reduction. Despite these advancements, such vehicles still represent a modest fraction of the total cars on Polish roads, as electromobility in the country is currently in its early stages of development. Nevertheless, research indicates a growing interest among drivers in considering cars with alternative propulsion, promising optimistic prospects for the future [91,92,93].

Policy measures, including subsidies for research and development, tax incentives, and funding for infrastructure projects, are crucial in supporting the hydrogen economy. Increased investment from the private sector, particularly in startups and innovative technologies, can drive rapid advancements and cost reductions. Governments around the world are investing in research initiatives aimed at reducing the reliance on platinum in fuel cell technology. For instance, the U.S. Department of Energy (DOE) funds programs such as the Fuel Cell Technologies Office (FCTO) that support research into alternative catalysts and cost reduction strategies.

Programs like the European Fuel Cells and Hydrogen Joint Undertaking (FCH JU) foster collaboration between industry, academia, and research institutions to develop next-generation fuel cell technologies. Universities sometimes establish spin-off companies to commercialize research findings. For example, companies like Ballard Power Systems originated from academic research and have grown to become leaders in the fuel cell industry. University incubators and accelerators support early-stage startups that are developing fuel cell technologies, providing them with resources (

Table 2. Case studies of successful collaborations.

Toyota and MIT Collaboration
Project overview: Toyota partnered with the Massachusetts Institute of Technology (MIT) to develop new catalyst materials that reduce platinum loading while maintaining high performance.	Outcomes: This collaboration has led to significant advancements in catalyst technology, contributing to the development of more cost-effective fuel cell vehicles.
Ballard Power Systems and University of British Columbia (UBC)
Project overview: Ballard Power Systems collaborates with UBC on several projects aimed at improving fuel cell performance and durability.	Outcomes: Joint research has resulted in the commercialization of new fuel cell technologies, helping Ballard maintain its position as a leader in the industry.
Hydrogen Europe and Imperial College London
Project overview: Hydrogen Europe, a coalition of industry stakeholders, collaborates with Imperial College London on research to enhance hydrogen production and storage technologies.	Outcomes: This partnership has produced innovative solutions for hydrogen infrastructure, facilitating the broader adoption of fuel cell technologies.
Shell and ITM Power
Project overview: Shell, a global energy company, collaborated with ITM Power, a specialist in hydrogen energy solutions.	Outcomes: Joint ventures to develop large-scale hydrogen refueling stations and electrolysis projects. Developed Europe’s largest hydrogen electrolysis plant in Germany. Expanded the hydrogen refueling network across the UK and Europe. Increased hydrogen production capacity from renewable sources. Improved infrastructure for hydrogen refueling, supporting fuel cell vehicles. Accelerated the adoption of hydrogen as a clean energy carrier.

), mentorship, and access to funding. Universities are forming consortia with industry partners to pool resources and expertise. Examples include the Hydrogen and Fuel Cell Center at the University of Birmingham, which works with companies like Toyota and Johnson Matthey on catalyst research. Programs that place PhD students in industry settings allow for direct collaboration on cutting-edge research projects, providing real-world applications for academic research.

These case studies highlight successful collaborations between various companies in the hydrogen fuel cell sector. These partnerships have significantly advanced the development of hydrogen infrastructure, increased the deployment of hydrogen-powered vehicles, and contributed to reducing carbon emissions across different industries. The collaborative efforts demonstrate the importance of combining expertise and resources to drive innovation and create sustainable energy solutions.

In 2022, hydrogen use in road transport increased significantly by about 45% compared to the previous year (as shown in Figure 7), although it started from a relatively low base. This growth is primarily attributed to the increased adoption of fuel cell electric vehicles (FCEVs), which initially found success in the passenger car and bus segments [94]. However, the market dynamics are changing as sales of heavy-duty fuel cell trucks continue to grow. Demand for these trucks is growing rapidly, contributing to a growing share of total hydrogen consumption in road transport. China, in particular, has become a leader in promoting the use of hydrogen in heavy-duty vehicles, making significant investments and policy commitments to support the sector. As a result, China has become a significant player in the deployment of fuel cell trucks. Although these heavy-duty vehicles only account for about 20% of the global FCEV fleet, they account for more than half of the hydrogen used in road transport worldwide [94]. This disproportionate share highlights the key role that heavy-duty applications play in the overall demand for hydrogen in the transportation sector.

Several factors are driving this trend, including government policies that support the development of clean energy solutions, financial incentives for the adoption of hydrogen vehicles, and advances in fuel cell technology that increase the efficiency and range of heavy-duty trucks. In addition, the establishment of extensive fueling infrastructure networks in key markets such as China has facilitated the increased deployment of these vehicles. Other regions around the world are also beginning to recognize the potential of hydrogen to decarbonize heavy-duty transportation. For example, Europe has seen an increase in investment in hydrogen-powered freight transport, driven by ambitious emission reduction targets and a supportive regulatory framework [95]. Similarly, North America has seen growing interest in hydrogen fuel cell trucks, particularly on long-haul routes where battery electric vehicles (BEVs) currently face range and charging time constraints. The global shift toward hydrogen in heavy-duty vehicles is expected to continue, with forecasts pointing to further growth in the coming years. As more countries invest in hydrogen infrastructure and technology, the share of hydrogen in the overall transport energy mix is expected to increase, largely driven by the increasing use of fuel cell trucks and buses.

The predominant utilization of hydrogen in transportation is expected to persist within the road sector for the foreseeable future. Nevertheless, there is a growing contribution from rail transportation as hydrogen trains undergo trials and are integrated into more routes [96,97]. Furthermore, the commencement of operations of several fuel cell ferries in 2023 broadened the spectrum of hydrogen applications in transportation [98]. The potential deployment of vessels capable of utilizing ammonia and methanol, coupled with their readiness for hydrogen, could further increase hydrogen consumption in shipping if these technologies achieve commercial viability in the near future.

In alignment with the net-zero emissions (NZE) scenario, the future use of synthetic kerosene and hydrogen as aviation fuels will significantly increase hydrogen consumption in transportation. To meet the NZE scenario targets, it is crucial to accelerate the adoption of hydrogen and hydrogen-based fuels and to advance pre-commercial technologies.

By the end of 2022, the number of fuel cell cars and vans in use surpassed 58,000 units, reflecting an almost 40% increase from the previous year, and it further rose to approximately 63,000 units by mid-2023 (Figure 8). In 2022, around 15,000 fuel cell cars were sold, with Korea contributing roughly two-thirds of this growth. However, the first half of 2023 saw a slowdown in Korea, with sales falling to fewer than 3000 units, down from nearly 4900 units during the same period the previous year, despite government plans to subsidize 16,000 fuel cell cars in 2023. Nonetheless, Korea remains the largest market for fuel cell cars globally, with a stock of over 32,000 units as of mid-2023. The United States follows with about 16,000 fuel cell cars on the roads. Although Japan holds the third-largest inventory of fuel cell cars, its sales dropped to fewer than 1000 units in 2022, while Europe saw higher growth, adding almost 1500 units. Notably, China deployed over 200 fuel cell cars in 2022, a significant achievement given its recent focus on heavier segments. As of June 2023, China leads in fuel cell light commercial vehicles, with over 800 units in operation.

Reflecting Korea’s authority in the fuel cell car market, Hyundai’s Nexo was the best-selling fuel cell car in 2022, with 10,000 units sold, followed by Toyota’s Mirai with 3200 units. Despite Honda discontinuing its fuel cell car production in 2021, both the SAIC EUNIQ7 and Honda Clarity sold around 200 units each in 2022. Additionally, BMW began small-series production of the iX5 Hydrogen fuel cell car in 2022, introducing their pilot fleet globally in early 2023. Future market expansions include Honda’s announcement of a new fuel cell vehicle based on the CR-V crossover SUV, set for US production in 2024. Moroccan startup NamX has also introduced a prototype fuel cell SUV, powered partly by replaceable hydrogen capsules, with a planned 2026 launch. Kia, Korea’s second-largest automaker, plans to introduce fuel cell cars starting in 2027. Furthermore, both Porsche and Toyota have developed prototype hydrogen cars using combustion engines, showcasing diverse technological approaches. However, fuel cell electric vehicles (FCEVs) remain a minority technology, with companies like Volkswagen focusing on battery electric vehicles. French startup Hopium aimed to launch a luxury fuel cell sedan in 2025 but entered receivership in July 2023.

In the light-commercial sector, new players such as First Hydrogen started trials of their “Generation I” fuel cell van in 2023 and are planning to develop a second-generation model soon. Similarly, RONN Motor Group announced intentions to produce fuel cell delivery vans and medium-duty trucks. Among established brands, Ford unveiled plans to test a fuel cell van trial in the United Kingdom.

The growth of fuel cell trucks has outpaced that of light-duty vehicles, with a 60% increase in 2022, reaching over 7100 units by year-end. By mid-2023, the stock had surged to over 8000 units. The vast majority of these sales occurred in China, which now holds over 95% of the global fuel cell truck market. This growth is mainly fueled by a more than fivefold increase in heavy-duty fuel cell trucks from the end of 2021 to June 2023, driven by supportive policies and infrastructure development. Additionally, fuel cell trucks are proving their effectiveness beyond China, with Hyundai’s Xcient logging 5 million kilometers in Switzerland since 2020 and expanding operations to Germany, Korea, and New Zealand.

According to CALSTART’s Zero-Emission Technology Inventory (ZETI), approximately 20 models of medium- and heavy-duty fuel cell trucks were available in 2022, with additional models anticipated in 2023. Fuel cell trucks, leveraging large hydrogen reserves, are ideal for high-payload applications, offering greater load capacity and extended range due to substantial hydrogen storage. Faster refueling times enable quicker turnarounds, making these trucks highly effective for time-sensitive tasks such as cold chain logistics. High availability further enhances their suitability for two-shift operations, offering flexibility across various routes [99].

8. Storage and Distribution Challenges

Hydrogen has low energy density, requiring efficient and safe storage solutions. Additionally, establishing a cost-effective and secure distribution system for hydrogen poses challenges that need to be addressed for a viable hydrogen economy.

Storage and distribution challenges are significant considerations in the development and expansion of a hydrogen infrastructure to support hydrogen fuel cell vehicles (HFCVs). Here are some key challenges in this regard:

• Low energy density and storage pressures

Hydrogen has a low energy density by volume, requiring high-pressure storage to store a sufficient amount of energy onboard HFCVs. This necessitates advanced storage materials and technologies capable of safely containing hydrogen at high pressures.

Very important parameters in the case of chemical hydrogen storage facilities are the mass capacity of hydrogen, the hydrogen release temperature, the reversibility of this process, and the purity of the released gas. These four physicochemical features allow us to determine whether a given material has a chance of success in further implementation research.

Due to the fact that the density of hydrogen gas is very low (0.0838 g/dm³ at 20 °C) [24], the tanks containing it would have to be unimaginably large for the range of cars powered by it to be satisfactory. That is why the DOE has determined the parameter of hydrogen volume capacity at the level of 30–50 g/dm³, i.e., the total density is approximately 500 times higher. To meet this challenge, other methods of storing hydrogen than its gaseous form must be used.

Additionally, the hydrogen mass capacity target set by the DOE is currently 6.5%. Even though this value may seem very small, meeting this requirement is not easy. It is worth remembering that the mass capacity of hydrogen is calculated as the ratio of the mass of hydrogen stored in the tank to the mass of the entire system—fuel with the tank and elements necessary to control the gas flow, e.g., cables. Therefore, the material of the tank and its filling are also important.

Another important parameter is the purity of hydrogen. Since one of the goals of replacing conventional fuels with hydrogen is to eliminate air pollution, the byproducts of releasing hydrogen from the tank cannot be other gases, especially toxic ones. Gases other than hydrogen can also poison electrodes, change the pH of the electrolyte, or damage membranes used in fuel cells, resulting in a significant reduction in their efficiency [25,26,27]. Moreover, in the case of chemical storage facilities, such a situation would cause potential problems with the reversibility of the process, i.e., charging the tank to which, in order to restore the state before discharge, other substrates apart from hydrogen would have to be supplied.

The issue of hydrogen release temperature is not clearly described in the DOE requirements. On the one hand, the tank should not release gas automatically, e.g., when the car is parked in a sunny place. This condition includes, among others, the ambient temperature parameter, which can range from −40 °C to 60 °C. On the other hand, the hydrogen supplied to the fuel cell cannot have a temperature higher than 85 °C (the use of low-temperature cells is assumed). This condition can be met in two ways: either the gas will be released at a temperature below 85 °C, or between the tank and the cell, it will be cooled to the desired temperatures. Due to the above conditions, the optimal hydrogen release temperature is 60–85 °C, but slightly higher values are also acceptable.

Metal hydrides are promising materials for hydrogen storage because they offer several advantages: they operate at relatively low pressures (typically 0.25–10 MPa), allow for the reversible absorption and release of hydrogen, can absorb hydrogen at low temperatures (even at room temperature), and are safe to use with minimal risk of explosion or flammability [100].

Low-temperature metal hydrides are the most popular due to the low temperatures at which hydrogen is absorbed. Desorption of hydrogen stored in metal hydrides usually occurs as a result of an increase in temperature and a reduction in the pressure of the system [101]. An example of a low-temperature hydrogen storage system is the Ti-Cr-Mn alloy, with a hydrogen sorption capacity of 1.9 m/m.

Another intriguing hydrogen storage material is palladium (Pd) and its alloys. Palladium can absorb hydrogen obtained as a result of electrochemical reactions as well as from the gas phase. It has been demonstrated that a palladium sample at room temperature can absorb hydrogen with a volume 850 times greater than its own volume. Hydrogen may exist in palladium in two phases: the α phase (forming a solid solution of hydrogen in palladium), which is formed at low hydrogen concentrations, and the β phase (constituting non-stoichiometric palladium hydride), which is formed when the amount of hydrogen absorbed by the metal increases [81].

The addition of metals such as ruthenium (Ru) and rhodium (Rh) to palladium increases the absorption capacity of the system. A Pd-Rh alloy containing 7% rhodium shows a more than 13% increase in the capacity of absorbed hydrogen compared to pure palladium. Although palladium and its alloys are interesting materials for storing hydrogen, their high acquisition costs mean that they are not currently widely used for hydrogen storage [102,103,104,105].

• Material compatibility and embrittlement

High-pressure storage can lead to issues such as embrittlement of materials used in tanks and pipelines. Identifying materials that are both strong and durable while avoiding hydrogen-induced embrittlement is a challenge in developing safe and reliable storage systems.

• Cost and weight of storage systems

Developing cost-effective and lightweight storage systems is essential for making HFCVs competitive with other technologies. Current storage solutions, such as carbon-fiber-reinforced composite tanks or metal hydride systems, can be expensive and add weight to vehicles [106,107,108].

• Infrastructure investment

Establishing a hydrogen distribution infrastructure, including pipelines and refueling stations, requires substantial investment. The cost of building and maintaining such infrastructure can be a barrier to widespread adoption, especially in regions where demand for hydrogen is not yet well established.

• Transportation logistics

The transportation of hydrogen from production facilities to distribution points and refueling stations poses logistical challenges. Ensuring a reliable and efficient supply chain is crucial for maintaining a steady and accessible hydrogen fuel supply.

• Safety concerns

Hydrogen is highly flammable, and safety concerns related to its production, storage, and distribution need to be addressed. Implementing safety measures, such as leak detection systems and emergency response protocols, is essential to gain public confidence in the technology.

• Hydrogen production proximity

The location of hydrogen production facilities in proximity to demand centers affects the efficiency of distribution. Strategic placement of production facilities can help minimize transportation distances, reduce costs, and optimize the overall hydrogen supply chain.

• Scaling up production

As the demand for hydrogen increases, scaling up production to meet this demand becomes a challenge. This involves overcoming limitations in current production methods and transitioning to more sustainable and scalable processes, such as green hydrogen production using renewable energy sources.

• International standardization

Standardizing storage and distribution systems internationally is crucial for interoperability and a seamless global hydrogen market. Achieving consensus on standards for components, refueling protocols, and safety measures is an ongoing challenge [109,110,111].

9. Hydrogen Vehicle Infrastructure and Investment Strategies

Building the infrastructure required to support hydrogen vehicles is one of the biggest challenges to their widespread adoption. Hydrogen vehicles require a new and comprehensive network of production, storage, distribution, and fueling infrastructure that is separate from the existing gasoline and electricity networks. This transformation requires significant capital investment, coordinated planning, and collaboration across sectors. Let us examine the challenges, potential solutions, and financing models for hydrogen infrastructure development [112].

High upfront capital costs: developing a hydrogen infrastructure network, including manufacturing plants, storage units, distribution pipelines, and fueling stations, requires significant upfront capital investment. For example, building a single hydrogen fueling station can cost about USD 1 million, which is significantly more than the cost of an electric vehicle (EV) charging station. In addition, the lack of economies of scale due to the current small number of hydrogen vehicles on the road makes it difficult to justify these high upfront costs. Currently, the number of hydrogen refueling stations is limited, which creates a problem: consumers are hesitant to purchase hydrogen vehicles due to the lack of refueling infrastructure, while investors are reluctant to finance refueling stations without a critical mass of vehicles. This shortage of refueling options is a significant barrier to consumer adoption of hydrogen vehicles, especially when compared to the growing network of electric vehicle charging stations [113].

The total number of hydrogen refueling stations (HRSs) has increased rapidly from 2015 to summer 2024, with 187 operational and accessible stations for public use (Figure 9). Most of them are located in Germany (86), France (27), and the Netherlands (24). The vast majority of HRSs have dispensers for refueling cars at a pressure of 700 bar. Around 50% of HRSs have dispensers that allow for refueling cars or buses, or both, at a pressure of 350 bar.

Hydrogen is a low-density gas that requires compression or liquefaction for storage and transportation. This process is energy-intensive and expensive. In addition, hydrogen must be stored at high pressures or low temperatures, which raises safety concerns and requires specialized infrastructure. Transporting hydrogen over long distances, whether by pipeline or truck, involves significant investment and faces technical challenges, especially in countries with little existing hydrogen infrastructure.

The development of hydrogen infrastructure is currently hampered by a fragmented regulatory environment. Different countries, and even regions within countries, have different safety regulations, standards, and incentives for hydrogen infrastructure, making it difficult to create a unified strategy for development. This lack of standardization increases costs, delays implementation, and reduces investor confidence.

Additionally, the uncertain pace of hydrogen vehicle deployment makes it difficult to accurately predict demand. This uncertainty discourages private investors from committing significant capital because they may not obtain a sufficient return on investment. Furthermore, consumer awareness and acceptance of hydrogen vehicles are still relatively low, further complicating the market outlook.

Public–private partnerships (PPPs) can be key to overcoming the high upfront costs and risks of developing hydrogen infrastructure. Governments can partner with private companies to share the costs, risks, and benefits. For example, public funds can be used to subsidize the construction of fueling stations, while private companies can operate them. Successful PPPs are found in Japan and South Korea, which have already begun building hydrogen infrastructure by combining government support with private investment [115].

To encourage the development of hydrogen infrastructure, governments can provide financial incentives such as tax breaks, grants, and subsidies to companies that invest in hydrogen production, storage, distribution, and refueling facilities. In the European Union, for example, the Hydrogen Strategy aims to promote investment in hydrogen technologies through funding programs and regulatory support. Similarly, the U.S. Infrastructure Investment and Jobs Act allocates billions for clean hydrogen projects, including infrastructure [116].

Focusing on strategic locations, such as urban centers, logistics hubs, and high-density transportation corridors, can help build an initial network of hydrogen fueling stations. For example, developing fueling stations along major highways or in specific metropolitan areas can help create a foundational infrastructure that supports early adopters, fleets, and commercial vehicles, fostering broader adoption.

Technological advances can lower the costs and improve the efficiency of hydrogen infrastructure. Innovations in hydrogen production, such as the use of cheaper catalysts for electrolysis, can lower the price of green hydrogen. Similarly, advances in storage and distribution technologies, such as solid-state hydrogen storage or more efficient compression methods, can reduce infrastructure costs and safety risks.

Establishing international standards for hydrogen production, storage, and distribution can lower costs and streamline infrastructure development. Standardization would provide clear guidelines for the construction and operation of hydrogen fueling stations and other infrastructure, reducing regulatory uncertainty and increasing investor confidence.

Existing infrastructure, such as gas pipelines and fuel stations, can be reused or upgraded to distribute and store hydrogen. This approach can reduce the need for entirely new infrastructure. For example, blending hydrogen with natural gas in existing pipelines can serve as a temporary solution to increase demand and reduce the costs associated with new hydrogen pipelines.

10. Economic and Social Aspects of Using Hydrogen in Vehicles

Hydrogen-powered vehicles, particularly fuel cell electric vehicles (FCEVs), are gaining popularity as a promising alternative to conventional gasoline-powered cars and battery electric vehicles (BEVs). Economic factors associated with hydrogen-powered vehicles include manufacturing costs, infrastructure, fuel, and potential social impacts [117].

• Manufacturing and development costs

The initial cost of manufacturing hydrogen-powered vehicles is significantly higher than that of conventional gasoline-powered vehicles and BEVs. This is primarily due to the cost of fuel cells, which use expensive materials such as platinum as catalysts. Currently, fuel cells are produced in small quantities, limiting economies of scale and keeping prices high. However, as the technology matures and production is scaled up, costs are expected to decline, potentially reaching parity with BEVs in the late 2020s or early 2030s.

• Fuel costs and availability

Hydrogen fuel is currently more expensive than gasoline or electricity. The price of hydrogen is influenced by production methods (such as electrolysis or steam reforming of methane), distribution, and storage. “Green hydrogen”, produced from renewable energy sources, is environmentally friendly but expensive, while “grey” and “blue” hydrogen, derived from fossil fuels, are cheaper but less environmentally friendly. The cost of green hydrogen is expected to fall with technological advances and scale-up, but it is uncertain when it will become competitive with traditional fuels [118,119].

• Infrastructure costs

One of the major economic challenges for hydrogen-powered vehicles is the infrastructure required to produce, store, and distribute hydrogen. Building a network of hydrogen fueling stations is expensive, with estimates ranging from USD 1 million to USD 2 million per station. For hydrogen-powered vehicles to become viable, especially for passenger vehicles, significant investment is needed to develop an extensive network of fueling stations. Governments and the private sector need to invest heavily in these areas, which may involve public subsidies or incentives.

• Maintenance and operating costs

Hydrogen-powered vehicles have fewer moving parts than internal combustion engines, which could lead to lower maintenance costs over time. However, the current shortage of specialist repair shops and parts could result in higher maintenance costs compared to electric vehicles or traditional vehicles. Over time, as the market develops and specialist skills become more widely available, these costs should decrease.

• Economic impact on the energy sector

The introduction of hydrogen-powered vehicles could significantly impact the energy sector. The shift towards hydrogen could reduce dependence on oil, which would affect countries that are heavily dependent on oil exports. On the other hand, it could create new opportunities for countries with abundant renewable energy resources to produce and export green hydrogen, potentially changing global energy markets [120].

It is also worth mentioning the social impact of hydrogen vehicles. The transition to hydrogen vehicles has the potential to trigger several societal changes [52]:

• Environmental impact

Hydrogen vehicles emit only water vapor, which reduces greenhouse gas emissions and air pollutants compared to conventional gasoline-powered vehicles. This can improve air quality, especially in urban areas, and help achieve global climate goals. However, the environmental benefits depend on how the hydrogen is produced. Green hydrogen, produced using renewable energy, offers the greatest benefits, while grey hydrogen, produced from fossil fuels, still produces CO₂ emissions [119].

• Energy security and geopolitical changes

Hydrogen can be produced locally from a variety of sources, including water and renewable energy, reducing dependence on imported oil and increasing energy security. This shift could alter global energy geopolitics by reducing the strategic importance of oil-rich regions and increasing the importance of regions with abundant renewable resources or the technological capacity to produce hydrogen.

• Job creation and economic opportunities

A hydrogen economy could create new jobs in manufacturing, infrastructure development, maintenance, and fuel production. Regions that invest in hydrogen technology could see significant economic growth similar to the boom in renewable energy. However, there could also be job losses in traditional fossil fuel industries, requiring retraining and transition programs for affected workers [116].

• Public health benefits

Reducing air pollution from hydrogen-powered vehicles could lead to significant public health benefits, including lower rates of respiratory and cardiovascular disease. This could reduce healthcare costs and improve overall quality of life, especially in urban areas with high vehicle emissions [118].

• Market adoption and consumer behavior

Adoption of hydrogen vehicles will largely depend on consumer perceptions and behavior. The current lack of refueling infrastructure and higher upfront costs may deter consumers, but government incentives, falling prices, and increased environmental awareness could drive adoption. In addition, hydrogen vehicles may be more attractive to consumers seeking faster refueling times and greater range than electric vehicles [118].

Hydrogen-powered vehicles present both economic opportunities and challenges. While the technology offers significant potential benefits for the environment, energy security, and public health, achieving widespread adoption will require overcoming significant cost and infrastructure barriers. The societal impact will depend largely on how governments, industries, and consumers respond to these challenges, the pace of technological progress, and the alignment of hydrogen production with sustainable energy goals [121,122].

Currently, the cheapest hydrogen is grey hydrogen, the price of which per kilogram is around two US dollars. Green hydrogen is unfortunately the most expensive to produce. Its price should not exceed USD 10 per kilogram. This amount results from various components, such as the costs of the entire infrastructure for electricity production, distribution, and the price of the installation for the production itself. Waste energy, reused to operate equipment and produce hydrogen, would allow for a reduction in the unit price of a kilogram of hydrogen in relation to green hydrogen. Waste energy can be recovered and used in various ways. Waste heat recovery involves using the heat generated as a byproduct of industrial processes for other purposes. When it comes to electricity, which is waste energy, we can expect it to be produced in the case of compressors used in industrial air conditioning, refrigeration systems, and in various production processes. When the gas is compressed, its temperature increases, which leads to the generation of waste heat. In some compressor systems, the excess of this heat is converted into electricity using steam turbines or thermoelectric generators. However, integrating waste energy recovery systems with existing industrial processes requires advanced technological and engineering solutions that are expensive. However, if hydrogen is produced from waste electricity, this can be another step towards increasing environmental decarbonization. Such an installation would require the use of appropriate electrolyzers. Water, which is also often available in industrial plants, would not constitute a major financial outlay. Then, thanks to water electrolysis, it would be possible to produce hydrogen. The price of a kilogram of hydrogen can vary significantly depending on the production method, location, scale of production, and market (

Table 3. Cost of hydrogen production in Europe [123].

Steam Methane Reforming (SMR)
For 2022, the levelized production costs of hydrogen by SMR in Europe were, on average, on approximately 6.23 EUR/kg of hydrogen.
Grid-connected electrolysis
The hydrogen production costs using grid electricity in Europe were estimated in range of 3.89–16.44 EUR/kg of hydrogen, with the average for all countries being 9.85 EUR/kg.
Water electrolysis with a direct connection to a renewable energy source (renewable hydrogen)
Hydrogen production costs via electrolysis with direct connection to a renewable energy source in Europe vary from 4.18 to 9.60 EUR/kg of hydrogen, with the average for all countries being 6.86 EUR/kg. Even though hydrogen production via electrolysis with a direct connection to a renewable energy source avoids electricity costs like network costs and taxes, the electrolyzer capacity factor is limited by the capacity factor of the renewable source it is connected to.

).

11. Key Startups and Patents in Hydrogen Fuel Cell Technology

Hydrogen fuel cell technology has seen significant innovation, with many startups leading the charge in developing new solutions and securing patents. Here are some key startups and notable patents in this space (

Table 4. The list of startups—a few examples that are focused on developing hydrogen fuel cell technology for cars and buses.

Riversimple
Location: United Kingdom	Riversimple is a British car manufacturer that specializes in hydrogen fuel cell electric vehicles (FCEVs). Its flagship model, the Rasa, is a lightweight, two-seater car designed for maximum efficiency and minimal environmental impact. The Rasa has a range of about 300 miles on a full tank of hydrogen and emits only water.
Hyundai Hydrogen Mobility (HHM)
Location: Switzerland (partnership between Hyundai and H2 Energy)	HHM is a joint venture between Hyundai and H2 Energy that focuses on deploying hydrogen fuel cell trucks in Switzerland. Although not a startup in the traditional sense, this partnership aims to provide hydrogen fuel cell solutions for heavy-duty transport, reducing carbon emissions in the logistics sector.
Loop Energy
Location: Canada	Loop Energy is a Canadian company that provides hydrogen fuel cell systems for commercial vehicles, including buses and trucks. Its technology aims to offer efficient and reliable fuel cell solutions to reduce greenhouse gas emissions in transportation.
Nikola Motor Company
Location: United States	Nikola is an American startup that develops hydrogen fuel cell trucks for long-haul transportation. Its vehicles, such as the Nikola Tre and Nikola Two, are designed to offer zero-emission solutions for the trucking industry. Nikola is also involved in building a hydrogen refueling infrastructure to support their vehicles.
Hyperion Motors
Location: United States	Hyperion Motors is a startup focused on producing high-performance hydrogen fuel cell vehicles. Its first vehicle, the XP-1, is a supercar that showcases the potential of hydrogen fuel cells in delivering high power and long range with zero emissions. The XP-1 aims to demonstrate the feasibility and advantages of hydrogen as a fuel for performance vehicles.
Hyzon Motors
Location: United States	Hyzon Motors specializes in hydrogen fuel cell-powered commercial vehicles, such as trucks and buses. Hyzon’s goal is to accelerate the adoption of hydrogen fuel cell technology in the commercial vehicle market, providing zero-emission solutions for logistics and public transportation.
Proterra
Location: United States	Proterra is known for its electric buses, but it has also been exploring hydrogen fuel cell technology. Its mission is to provide clean, quiet transportation options for urban environments, and its developments in hydrogen fuel cell buses aim to extend the range and efficiency of their electric vehicle offerings.
Wrightbus
Location: United Kingdom	Wrightbus is a UK-based company that has developed the world’s first hydrogen double-decker bus. It aims to provide zero-emission public transportation solutions, and its hydrogen buses are designed to offer the same range and performance as traditional diesel buses while producing only water vapor as an emission.
New Flyer Industries
Location: Canada/United States	New Flyer is a leading manufacturer of transit buses and has been developing hydrogen fuel cell buses as part of its Xcelsior CHARGE H2™ line. Its hydrogen buses are designed for long-range, zero-emission transit operations, providing a sustainable alternative for public transportation networks.
Van Hool
Location: Belgium	Van Hool is a Belgian manufacturer that produces hydrogen fuel cell buses. Its A330 and Exqui. City models are designed to offer efficient and environmentally friendly public transportation options. Van Hool’s hydrogen buses are already in operation in several cities across Europe.
Caetanobus
Location: Portugal	Caetanobus is a Portuguese bus manufacturer that has developed the H2. City Gold, a hydrogen fuel cell bus. This bus is designed for urban transit and aims to provide a zero-emission solution with the same reliability and comfort as traditional buses. The H2. City Gold is part of Caetanobus’s effort to lead in sustainable public transportation solutions.

).

These startups represent a growing trend in the automotive industry towards sustainable and clean energy solutions, leveraging hydrogen fuel cell technology to reduce environmental impact and reliance on fossil fuels. These startups and companies are pushing the boundaries of hydrogen fuel cell technology, providing innovative solutions to reduce emissions and improve sustainability in public transportation.

In recent years, there has been a surge in patent filings related to hydrogen fuel cell technology, reflecting significant advancements in various aspects of the technology, from fuel cell design to hydrogen production and storage solutions. Below are some notable patents that highlight these innovations (

Table 5. The list of patents—a few examples that are focused on developing hydrogen fuel cell technology for cars and buses.

Fuel Cell Design Innovations
Advanced catalyst structures: Platinum and platinum-based alloy nanotubes as electrocatalysts for fuel cells	US Patent No. 2009/0220835 A1: This patent focuses on the development of efficient catalysts for proton exchange membrane (PEM) fuel cells. It describes the use of nanostructured platinum alloys that improve catalytic activity and reduce platinum loading, enhancing overall fuel cell efficiency and reducing costs.
Improved membrane technology: Development of novel proton-conductive polymers for proton exchange membrane fuel cell (PEMFC) technology	US Patent No. 7,615,300 B2: This patent details a novel proton exchange membrane with enhanced conductivity and durability. The membrane incorporates advanced materials such as sulfonated polyaryl ether ketones, which improve the performance and longevity of PEM fuel cells.
High-performance bipolar plates: Composite bipolar plate for a fuel cell and method	DE Patent No. 102004043513 A1: This patent introduces a new design for bipolar plates used in fuel cells. The plates are made from lightweight composite materials with optimized flow field patterns, which enhance gas distribution and reduce pressure drops, leading to higher fuel cell efficiency and performance.
Hydrogen production methods
Efficient electrolysis systems and others: Power dispatch system for electrolytic production of hydrogen from wind power	Patent No. WO2010/048706 A1: This patent describes an advanced electrolyzer system that uses renewable energy sources such as solar or wind power to produce hydrogen. The system incorporates high-efficiency electrolyzer stacks and innovative power management techniques to maximize hydrogen output while minimizing energy consumption.
Hydrogen-producing fuel cell systems and methods of operation	US Patent No. 2024/0063411 A1: The methods include initiating supply of a stored hydrogen stream, which includes stored hydrogen gas, to a fuel cell stack. Prior to initiating, the stored hydrogen gas is stored in a low-pressure hydrogen storage tank at a hydrogen storage pressure. The methods also include generating an electrical power output from the stored hydrogen gas with the fuel cell stack. The methods further include, during a supply time interval that is subsequent to initiating, monitoring a hydrogen supply variable that is indicative of flow of the stored hydrogen stream to the fuel cell stack. The methods also include detecting changes in the hydrogen supply variable and responding to them.
Method for producing hydrogen	US Patent No. 6,506360 B1: The hydrogen production method described involves reacting aluminum with water in the presence of sodium hydroxide as a catalyst. The equipment used for this process regulates the reaction’s intensity and duration by adjusting the pressure and temperature, which in turn controls the extent to which a fuel cartridge is submerged in water.
Photocatalytic hydrogen production: Photocatalytic hydrogen production from water over mixed-phase titanium dioxide nanoparticles	Patent No. WO2016/005855 A1: This patent covers a method for producing hydrogen using photocatalysts that harness sunlight. The process involves the use of nanostructured titanium dioxide (TiO2) combined with other semiconductors to enhance the efficiency of water splitting under solar illumination.
Photocatalytic hydrogen production from water over Ag-Pd-Au deposited on titanium dioxide materials	Patent No. WO2015/118424 A1: Photocatalysts and methods for generating hydrogen from water are described. The photocatalysts include photoactive titanium dioxide particles with an anatase-to-rutile ratio of at least 2:1, combined with silver, palladium, and gold metals deposited on the titanium dioxide surface. The molar ratio of gold to palladium ranges from 0.1 to 5, and the ratio of gold to silver ranges from 0.1 to 3.
Biological hydrogen production: Microorganism having a gene for improved hydrogen-generating capability, and process for producing hydrogen	US Patent No. 2007/0202585 A1: This patent details a method for producing hydrogen using genetically engineered microorganisms. The microorganisms are modified to enhance their hydrogenase activity, allowing them to efficiently convert organic substrates into hydrogen gas.
Hydrogen storage solutions
High-capacity metal hydrides: Metal hydrides and their use in hydrogen storage applications	US Patent No. 9,376,316 B2: This patent describes the use of advanced metal hydrides for hydrogen storage. The metal hydrides have high hydrogen absorption capacities and can release hydrogen at moderate temperatures, making them suitable for onboard storage in hydrogen-powered vehicles.
Nanotube storage: Apparatus with large-surface-area nanostructures for hydrogen storage, and methods of storing hydrogen	US Patent No. 2010/0276304 A1: Method and apparatus for storing hydrogen. In one embodiment, the method involves using a storage device that includes a substrate with a nanostructure mat applied to at least one side. This nanostructure mat consists of multiple nanostructures with a surface ionization state that enables the adsorption of multiple hydrogen layers. The process also includes exposing the nanostructure mat to hydrogen, allowing it to adsorb more than one layer of hydrogen onto the nanostructures.
Liquid organic hydrogen carriers: Hydrogen storage by means of organic liquid compounds	FR Patent No. 3115031 A1: This patent details a system for storing and transporting hydrogen using liquid organic hydrogen carriers. LOHCs can absorb and release hydrogen through chemical reactions, offering a safe and efficient way to handle hydrogen fuel.
Integrated systems and applications
Fuel cell integration in vehicles: Integrated fuel cell system	US Patent No. 6,376,113 B1: This patent covers an integrated fuel cell system for automotive applications. The system includes a compact fuel cell stack, onboard hydrogen storage, and power management electronics, optimized for use in passenger vehicles to achieve high efficiency and performance.
Hydrogen fuel cell hybrid locomotives	US Patent No. 8,117,969 B1: A hydrogen hybrid locomotive features a battery system that powers multiple electric traction motors for moving the locomotive along railroad tracks, along with a fuel cell power plant that charges the batteries and drives the electric motors. The fuel cell power plant includes one or more fuel cell modules that generate electrical current by reacting hydrogen fuel with oxygen from the intake air, with the amount of current being proportional to the air mass flow. An air system provides the necessary air mass flow to the fuel cell module to produce the required electrical current for the locomotive’s operating conditions. Additionally, a cooling system manages the temperature of the fuel cell power modules based on the current being produced.
Portable fuel cell systems: Portable hydrogen generator and fuel cell system *	US Patent No. 2006/0112635 A1: This patent describes a portable fuel cell system designed for use in remote or off-grid applications. The system is lightweight, compact, and includes integrated hydrogen storage and power conditioning units, making it ideal for mobile power generation.
Station: Hydrogen fueling station	US Patent No. 6,510,925 B2: This patent details the design of an advanced hydrogen refueling station. The station includes high-efficiency compressors, cryogenic storage tanks, and automated dispensing systems to ensure fast and safe refueling of hydrogen-powered vehicles.
High-efficiency hydrogen tanks: Hydrogen storage tank	US Patent No. 8,628,609 B2: This patent focuses on high-pressure hydrogen storage tanks that use advanced composite materials to achieve high storage densities while maintaining safety standards. The tanks are designed to fit into existing vehicle frameworks without significant modifications, facilitating easier integration into new and retrofitted vehicles.
Onboard hydrogen generation methods and system for hydrogen production by water electrolysis	US Patent No. 10,487,408 B2: This patent covers a system for onboard hydrogen generation using water electrolysis powered by renewable energy sources. The system is designed to produce hydrogen as needed, reducing the dependency on hydrogen refueling infrastructure and enabling longer travel distances between refueling stops.
System and method for generating hydrogen gas	US Patent No. 2007/0138006 A1: A hydrogen gas generation system is designed for use in various mobile vehicles, such as cars, trucks, balloons, dirigibles, airships, ships, or boats. This system includes an onboard hydrogen generator that produces hydrogen gas, preferably through an electrolysis process. The generated hydrogen is stored in an onboard storage tank. The stored hydrogen is then supplied to the vehicle’s propulsion system, where it is used to generate power for moving the vehicle. Additionally, an onboard electrical generation system provides some of the electricity needed for the electrolysis process. For instance, the vehicle may be equipped with an onboard electrical generator that supplies the necessary electricity for hydrogen production.
Power electronics and control systems
Integrated power management system: Fuel cell power system and method of controlling a fuel cell power system **	US Patent No. 6,743,536 B2: This patent describes an integrated power management system that optimizes the flow of electricity between the fuel cell stack, battery, and electric motor. The system includes advanced algorithms that manage power distribution in real time, improving overall vehicle efficiency and performance.
High-efficiency inverters: Hybrid fuel cell vehicle with multi-power source and multi-drive system and method of control	US Patent No. 8,016,061 B2: This patent focuses on a new design for inverters used in fuel cell vehicles. The inverters are more efficient and compact, enabling better integration into vehicle electrical systems and improving the conversion of DC power from the fuel cell to AC power for the electric motor.
Thermal management solutions
Advanced cooling systems: Cooling system for a fuel cell stack ***	US Patent No. 6,866,955 B2: This patent introduces an advanced cooling system that uses a combination of liquid cooling and phase-change materials to manage the heat generated by the fuel cell stack. The system is designed to maintain optimal operating temperatures under various driving conditions, enhancing the durability and performance of the fuel cell.
Heat recovery systems: Waste heat recovery means for fuel cell power system	US Patent No. 6,926,979 B2: This patent describes a heat recovery system that captures and utilizes the waste heat from the fuel cell stack to improve vehicle efficiency. The recovered heat can be used for cabin heating or to pre-heat the fuel cell stack, reducing energy consumption and improving cold-start performance.
Vehicle integration techniques
Compact integration framework: Vehicle mounting structure for fuel cell	US Patent No. 7,533,748 B2: This patent covers a compact integration framework for fuel cell systems in vehicles. The framework includes a specially designed chassis and mounting system that accommodates the fuel cell stack, hydrogen tanks, and associated components without compromising vehicle design and functionality.
Structural integration: Structural fuel cells and components thereof	US Patent No. 8,057,938 B1: This patent details a method for integrating fuel cell components into the structural elements of the vehicle, such as the frame and body panels. This approach not only saves space but also enhances the vehicle’s structural integrity and safety.

* (1). S. C. Amendola et al., “Differential Pressure-Driven Borohydride Based Generator”, U.S. patent application Ser. No. 09/902,899 (filed 11 July 2001). (2). S. C. Amendola et al., “Portable Hydrogen Generator”, U.S. patent application Ser. No. 09/900,625 (filed 7 July 2001). (3). M. Strizki et al., “Self-regulating Hydrogen Generator”, U.S. patent application Ser. No. 10/264,302 (filed 3 October 2002). (4). M. Strizki et al., “Hydrogen Gas Generation System”, U.S. patent application Ser. No. 10/359,104 (filed 5 February 2003). (5). S. C. Amendola et al., “System for Hydrogen Generation”, U.S. patent application Ser. No. 10/638,651 (filed 1 August 2003). (6). R. M. Mohring et al., “System for Hydrogen Generation”, U.S. patent application Ser. No. 10/223,871 (filed 20 August 2002). (7). P. J. Petallo et al., “Method and System for Generating Hydrogen by Dispensing Solid and Liquid Fuel Components”, U.S. patent application Ser. No. 10/115,269 (filed 2 April 2002). ** U.S. Pat. No. 6,028,414 to Chouinard et al.; U.S. Pat. No. 5,916,699 to Thomas et al.; and U.S. Pat. No. 5,401,589 to Palmer et al. *** U.S. Pat. No. 5,663,113.; U.S. Pat. No. 5,766,624.

).

The integration of fuel cell technology into vehicles is a rapidly evolving field, as evidenced by the numerous patents filed in recent years. These patents showcase significant advancements in fuel cell stack design, hydrogen storage, power electronics, thermal management, and overall vehicle integration. Continued innovation and collaboration between industry and academia are essential to overcome current challenges and make hydrogen-powered vehicles a mainstream reality.

The International Organization for Standardization (ISO) has developed several standards related to fuel cells and the use of hydrogen in the automotive industry. These standards cover various aspects such as safety, performance, testing methods, and terminology.

Table 6. The list of example procedures of the ISO.

ISO Standards for Fuel Cells
ISO 14687:2019—Hydrogen fuel quality	This document outlines the quality characteristics required for hydrogen fuel used in proton exchange membrane (PEM) fuel cell applications in road vehicles. It defines the minimum quality standards for hydrogen fuel to ensure its suitability for both vehicular and stationary applications.
ISO 16111:2008 (new ISO 16111:2018)—Transportable gas storage devices—Hydrogen absorbed in reversible metal hydride	Provides the specifications and testing methods for transportable hydrogen storage devices using metal hydrides. Defines the requirements applicable to the material, design, construction, and testing of transportable hydrogen gas storage systems, referred to as “metal hydride assemblies” (MH assemblies) which utilize shells not exceeding 150 l internal volume and having a maximum developed pressure (MDP) not exceeding 25 MPa (250 bar).
ISO 22734:2019—Hydrogen generators using water electrolysis	Specifies the safety requirements for hydrogen generators that use water electrolysis. This document specifies the construction, safety, and performance standards for modular or factory-matched hydrogen gas generation systems, referred to as hydrogen generators. These systems use electrochemical reactions to electrolyze water and produce hydrogen.
ISO 14687-2:2012 (new ISO 14687:2019)—Hydrogen fuel—Product specification—Part 2: Proton exchange membrane (PEM) fuel cell applications for road vehicles	Defines the product specification for hydrogen fuel in PEM fuel cell applications, specifically for road vehicles. The document details the quality characteristics of hydrogen fuel to ensure consistency in the hydrogen product used for proton exchange membrane (PEM) fuel cell systems in road vehicles.
ISO 26142:2010—Hydrogen detection apparatus	Specifies the specifications for hydrogen detection devices designed to improve safety. This international standard outlines the performance criteria and testing for hydrogen detection equipment intended to measure and monitor hydrogen concentrations in stationary applications.
ISO standards for hydrogen use in the automotive industry
ISO 19880-1:2020—Gaseous hydrogen—Fueling stations—Part 1: General requirements	Establishes the general requirements for the design, construction, operation, and maintenance of hydrogen fueling stations. This document specifies the minimum requirements for the design, installation, commissioning, operation, inspection, and maintenance of both public and private hydrogen fueling stations that provide gaseous hydrogen to light-duty road vehicles, such as fuel cell electric vehicles. It does not apply to the dispensing of cryogenic hydrogen or hydrogen to metal hydride applications.
ISO 17268:2012 (new ISO 17268:2020)—Gaseous hydrogen land vehicle refueling connection devices	Defines the specifications for connectors used in refueling hydrogen land vehicles. This document defines the design, safety, and operation characteristics of gaseous hydrogen land vehicle (GHLV) refueling connectors. This includes details on the receptacle and protective cap (mounted on the vehicle) and the nozzle.
ISO 23828:2013 (new ISO 23828:2022)—Fuel cell road vehicles—Energy consumption measurement—Vehicles fueled with compressed hydrogen	This document outlines the methods for measuring the energy consumption of fuel cell road vehicles powered by compressed hydrogen. It details the procedures for assessing the energy use of fuel cell passenger cars and light-duty trucks that rely on compressed hydrogen and are not capable of external charging.
ISO 14687-1:1999 (new ISO 14687:2019)—Hydrogen fuel—Product specification—Part 1: All applications except proton exchange membrane (PEM) fuel cell for road vehicles	Provides the product specifications for hydrogen fuel for all applications except PEM fuel cells for road vehicles. This international standard defines the quality characteristics of hydrogen fuel to ensure consistency and uniformity in the hydrogen product as it is produced and distributed for use in vehicles, appliances, or other fueling applications.
ISO 12619-3:2014 series—Road vehicles—Compressed hydrogen gas (CGH2) and hydrogen/natural gas blend fuel system components	A series of standards that specify the requirements for components used in compressed hydrogen gas and hydrogen/natural gas blend fuel systems for road vehicles. This document specifies general requirements and definitions for fuel system components designed for compressed gaseous hydrogen (CGH2) and hydrogen/natural gas blends, intended for use in motor vehicles as defined in ISO 3833.
Other relevant standards
ISO/TR 15916:2015—Basic considerations for the safety of hydrogen systems	Provides guidance on the safety considerations for the design and operation of hydrogen systems. This document offers guidelines for the use of hydrogen in both its gaseous and liquid states, as well as for its storage in these or other forms such as hydrides. It outlines fundamental safety concerns, hazards, and risks and details the properties of hydrogen that are pertinent to safety considerations.
ISO 13984:1999—Liquid hydrogen—Land vehicle fuel tanks	Specifies the requirements for fuel tanks designed to hold liquid hydrogen for land vehicles. This international standard applies to the design and installation of liquid hydrogen (LH2) fueling and dispensing systems. It covers the system designed for dispensing liquid hydrogen to a vehicle, including that portion of the system components that manage cold gaseous hydrogen from the vehicle’s tank, specifically addressing the system components situated between the land vehicle and the storage tank.
GB/T 29126-2012—Fuel cell electric vehicles—Onboard hydrogen system—Test methods	This standard outlines the test methods for the onboard hydrogen system of fuel cell electric vehicles. It applies to fuel cell electric vehicles that use compressed hydrogen as fuel, where the operating pressure does not exceed 35 MPa at an ambient temperature of 15 °C.

contains information about ISO standards.

These standards are crucial for ensuring the safe and efficient use of hydrogen and fuel cell technologies in the automotive industry. They help harmonize practices, ensure compatibility, and maintain safety across different regions and manufacturers.

The battery technology landscape is rapidly evolving, driven by the need for more efficient, durable, and sustainable energy storage solutions across sectors such as electric vehicles (EVs), consumer electronics, grid storage, and renewable energy integration. Startups play a key role in this ecosystem, driving innovation, exploring new battery chemistries, and developing advanced materials and manufacturing techniques (

Table 7. Key startups and patents in the battery technology landscape.

Startup	Patent
QuantumScape (solid-state batteries)
QuantumScape, a Silicon Valley startup, is focused on developing lithium-metal solid-state batteries that promise to revolutionize the electric vehicle industry with higher energy density, faster charging capabilities, and improved safety compared to traditional lithium-ion batteries.	QuantumScape has a strong portfolio of patents related to solid-state battery technology. These patents cover innovations such as ceramic separators, electrolyte compositions, and methods for stabilizing lithium-metal anodes. The company’s patents are key to securing its technological edge and have been a key factor in attracting major investors such as Volkswagen.
Solid Power (solid-electrolyte batteries)
Solid Power is another notable startup working on solid-state batteries, focusing on using sulfide-based solid electrolytes to improve energy density and safety. The company aims to replace liquid electrolytes in lithium-ion batteries with a solid electrolyte that prevents the formation of dendrites that can cause short circuits.	Solid Power holds patents related to solid-state electrolyte materials, battery cell architecture, and manufacturing processes. Its patent portfolio helps it protect its unique approach to battery technology and has been instrumental in forging partnerships with industry giants like BMW and Ford.
Form Energy (iron–air batteries)
Form Energy is a pioneer in the development of iron–air batteries, a novel energy storage solution designed for long-term grid storage. These batteries use abundant and cheap iron to store energy, making them an attractive option for large-scale energy storage, especially to offset intermittent renewable energy sources such as wind and solar.	The company’s patent strategy focuses on the unique chemistry and design of iron–air batteries, including methods for managing oxygen flow, electrode materials, and cell configurations. These patents protect its core technology and facilitate entry into the energy storage market.
Sila Nanotechnologies (silicon anode batteries)
Sila Nanotechnologies is working on next-generation batteries, replacing traditional graphite anodes with silicon-based anodes that offer higher energy density and longer battery life. This innovation is particularly relevant for consumer electronics and electric vehicles, where there is a high demand for improved battery performance.	Sila Nanotechnologies has secured numerous patents covering silicon-dominant anode compositions, nanostructured materials, and manufacturing techniques. These patents provide a competitive advantage in a market with high demand for high-energy density and long-life batteries and have attracted partnerships with companies such as Daimler and BMW.
Ambri (liquid metal batteries)
Ambri develops liquid metal batteries for grid-scale energy storage. Its technology uses a liquid calcium alloy anode, a molten salt electrolyte, and a solid antimony cathode. These batteries are designed to offer low-cost, long-lasting, and safe energy storage for renewable energy integration.	Ambri holds several patents on liquid metal battery technology, including unique cell designs, electrode materials, and manufacturing processes. These patents are essential to securing financing and partnerships with utilities and grid operators who are increasingly interested in scalable, cost-effective energy storage solutions.

). Patents, in turn, provide a key mechanism to protect these innovations, enabling startups to attract investment, form strategic partnerships, and compete in a technology-driven marketplace.

12. Conclusions

The essence of replacing electric cars with hydrogen-powered vehicles lies in addressing some of the key challenges associated with electric transportation. From extended driving ranges and reduced charging times to zero emissions, hydrogen cars offer a promising alternative for a sustainable and eco-friendly future. While infrastructure development remains a critical factor, ongoing technological advancements and growing support for hydrogen as a clean energy source position it as a game-changer in the realm of transportation. As global initiatives towards decarbonization gain momentum, hydrogen-powered vehicles are poised to play a pivotal role in reshaping the landscape of sustainable mobility.

The high cost of platinum and other rare materials has been a major barrier to the widespread adoption of fuel cell technology in hydrogen-powered vehicles. However, ongoing research and development efforts are making significant strides in reducing reliance on these materials and lowering overall costs. Through advancements in catalyst technology, industry collaboration, and supportive policy measures, fuel cells have the potential to become a more economically viable and sustainable solution for future transportation needs.

Collaborative efforts between industry and academia are pivotal in overcoming the cost challenges associated with platinum in fuel cell technology. Through joint research initiatives, technology transfer, and focused R&D, significant progress is being made toward more affordable and sustainable hydrogen-powered vehicles. Continued investment and innovation in this space will be essential for the widespread adoption of fuel cell technology.

This manuscript provides a comprehensive overview of the current state and future prospects of hydrogen-powered vehicles, including insights into cost competitiveness, research efforts, and the innovative landscape shaped by startups and patents.